Mission Brief

The Reference Every Element Trusts

The metering, the sync-check and every directional element on this 115 kV bay read their voltage from one VT. A small ratio error skews the revenue metering; a reversed polarity blocks synchronising and flips the directional angle 180°. Before any of it goes live, prove the VT: ratio, polarity, burden, and the accuracy class.

• Verify VT turns ratio and polarity
• Understand accuracy class as voltage error + phase displacement
• Check the measured error against the class limit box (IEC 61869-3)
• Confirm the connected burden is within rating
• Issue a pass/fail VT test record